The purpose of this project is first to identify and then to modify psychosocial factors associated with adherence to the regimens of persons with non-insulin dependent diabetes mellitus (NIDDM). Two major studies are proposed. The first, designed to replicate and extend the findings of our current research with IDDM patients, will consist of a prospective assessment of approximately 100 NIDDM patients between the ages of 30 and 60. At two intervals, separated by 6 months, participants will complete psychosocial measures, and their levels of regimen adherence and metabolic control will be assessed. Psychosocial measures will be drawn from Social Learning Theory and will include regimen specific knowledge, beliefs and expectations (e.g., self-efficacy), diabetes-specific coping skills and stress management strategies (e.g., problem solving skills), and incentives for adherence (e.g., levels of family support). Adherence will be assessed via multiple measures (questionnaires, self-monitoring records, and objective indices such as activity monitors) in each of four areas: dietary behavior, physical activity, glucose testing, and medication adherence. Metabolic control will be assessed using glycosylated hemoglobin (HbA1c), fasting blood glucose levels, and daily glucose testing records. Based in part upon the findings in the first study, a comparative treatment outcome experiement will be conducted to test treatment programs designed to increase adherence to dietary and exercise prescriptions. Within-subject pilot studies will be conducted to refine treatment interventions based on self-management and coping strategies used by good adherers. Then, 60-72 overweight NIDDM patients will be randomly assigned to one of 3 conditions: (1) treatment emphasizing the use of "subject derived" strategies for maintaining adherence; (2) treatment using more standard behavior management strategies; and (c) treatment using health education only. Treadmill fitness testing, as well as measures of adherence and metabolic control similar to those employed in the first study, will be used to evaluate response to treatment at posttest and during a 6-month follow-up period.